Apparatus for charging a receptacle with a dense sublimate form of uranium chloride



Aug 18, 1959 Filed April 5, 1946 P. H. DAVIDSON APPARATUS FOR CHARGING A RECEPTACLE WITH A DENSE SUBLIMATE FORM OF URANIUM CHLORIDE 4 Sheets-Sheet 1 PHIL/P H. DA W05 ON BY W4 ATTORNEY.

Y Aug. 18, 1959 P. H. DAVIDSON APPARATUS FOR CHARGING A RECEPTACLE WITH A DENSE SUBL IMATE FORM OF URANIUM CHLORIDE 4 Sheets-Sheet Filed April 5, 1946 v INVENTORA PHIL/P H. DA l//0$ ON f. r I

ATTORNEY.

Aug. 18, 1959 P- H. DAVIDSON 2,900,237

APPARATUS FOR bHARGING A RECEPTACLE WITH A DENSE SUBLIMATE FORM OF URANIUM CHLORIDE Filed April 5,' 1946 4 Sheets-Sheet 4 Fig. 1.9. 12 19.

mulllggl 4- film-V5 v V /04 INVENTOR.

PHIL/P H. DA vlosolv 2,900,237 Patented Aug. 13, 1959 APPARATUS FOR CHARGING A RECEPTACLE.

WITH A DENSE SUBLHVIATE FORM OF URA- NIUlVI CHLORIDE Philip H. Davidson, Visalia, ,Califl, assignor to the United States of America as represented by the United States Atomic Energy Commission Application April 5,1946, Serial No. 659,715

Claims. (Cl. 23264) This invention relates generally to the production of dense, compact masses of normally solid, sublimable materials, for example certain uranium compounds, and especially to the deposition from their vapors of sublimable halides of uranium in massive form. More particularly, it pertains to the loading of storage receptacles, or charge bottles such as are used in charging calutron Vaporizers, by condensing in situ vapors of sublimable halides of uranium, such as uranium tetrachloride or uranium hexachloride, into compact'coherent cakes of the respective halide in such receptacles or charge bottles.

There is a present need for large quantities of the uranium isotope having mass number 235. Uranium as obtained from natural sources comprises the aforementioned isotope mixed with two others having the mass numbers 234 and 238, in the ratio U :U :U l: 120: 16,700.

An apparatus capable of elfecting a separation of desired components from a mixture of these isotopes is called a calutron. Such a calutron essentially comprises means for vaporizing a quantity of material containing an element (for example, uranium) which is to be enriched with 'a selected one of its plurality of isotopes; means for subjecting the vapor to ionization, whereby at least a portion of the vapor is ionized causing ions of the several isotopes of the element to be produced; electrical means for segregating the ions from the un-ionized vapor and for accelerating the segregated ions to relatively high velocities; electromagnetic means for deflecting the ions along curved paths, the radii of curvature of the paths of the ions being proportional to the square roots of the masses of the ions, whereby the ions are concentrated in accordance with their masses; and means for de-ionizing and collecting the ions of the selected isotopes thus concentrated, thereby to produce a deposit of the element enriched with the selected isotope.

The device for supplying the vapor of a material, such as a uranium compound, that is to be treated in a calutron ordinarily comprises a heater with a tubular chamber in which is set a receptacle or vaporizing vessel, commonly called a charge bottle, containing a charge of a uranium compound that volatilizes readily upon heating Uranium hexachloride, which can be satisfactorily sublimed at about 100 C. under a vacuum corresponding to an absolute pressure not exceeding approximately mm. mercury, has been found to be especially suitable for charging these devices. Likewise uranium tetrachloride, although normally less volatile than thehexachloride, is suitable for this purpose. Both uranium tetrachloride and uranium hexachloride are highly hygroscopic compounds and decompose readily when exposed to ordinary atmospheric conditions.- v I Usually the charge bottles are filled with the desired charge itself, so that vapor is furnished at the desired j uranium compound, such as UCl or UCl in granular .form, whereupon they are sealed against the deleterious action of ordinary atmospheric air and stored until needed for charging the calutron preparatory to making a run The amount of uranium-containing vapor suptherein. plied to the ionization chamber of the calutron is ordinarily regulated by controlling the amount of heat applied to the charge of raw material for vaporization thereof. With the charge material in granular form, however,

previous efforts to quickly bring about and thereafter maintain uniform temperature conditions within the steady rate, have not been completely satisfactory.

One object of this invention is to provide a storage receptacle or charge bottle containing a sublimable, normally solid material in dense massive form.

A further object is to prepare sublimable uranium compounds, and especially the halides of uranium such as the tetrachloride and the hexachloride, in the form of compact coherent blocks or cakes deposited in situ in 'storage' receptacles and the like.

It is also an object of this invention to provide a charge bottle containing source material for a calutron in such form as will improve the operating characteristics of the calutron vaporizer, and hence of the calutron itself.

Another object is to prepare a calutron charge, especially of a sublimable, normally solid uranium compound such as the tetrachloride or the hexachloride, in such a condition that the time required to establish conditions of uniform heat transfer between the charge and its heater will be materially decreased.

Still further objects are to provide storage receptacles or charge bottles containing dense masses of uranium tetrachloride or uranium hexachloride, to provide vessels loaded with a sublimable uranium chloride in the form of blocks, to provide massive bodies of uranium chloride which have high heat conductivity, to'deposit uranium chloride in a form that transfers heat'readily, to provide calutron charges of sublimable uranium chloride in mas-t ,general advance in the art and other objects which will appear hereinafter are also contemplated.

I have discovered that storage receptacles or charge bottles containing a normally solid, sublimable material in the form of dense, massive blocks or mases may be prepared by flowing vapor of the material into contact with a surface of the receptacle or charge bottle that is sufficiently cooled to effect condensation thereof from the vapor phase directly to the solid phase (i.e., below the triple point of the sublimable material), and preferably while maintaining conditions of temperature and pressure within the condensing zone defined by the wallsof the receptacle or charge bottle such that the molecular density of the vapor of the material undergoing processing has a value providing a mean free path for the molecules that is a body of a vaporizable compound, such as uranium tetrachloride or uranium hexachloride, and the heater therefor in a calutron vaporizer enclosing the same is decreased if the charge has been preformed into a dense cake of the compound by progressively condensing the vapor of the uranium chloride or other compound in situ in the charge bottle, and preferably under conditions such that the majority of vapor molecules always strike the end rather than the side walls of the charge bottle.

How the foregoing objects and related ends are accomplished will be apparent from the following exposition in which are disclosed the principle, the organization and various embodiments of the invention, including the best mode contemplated for carrying out the same. he written description is amplified by the accompanying drawings, in which for greater clarity certain parts are shown in more or less conventionalized manner and certain parts are shown out of proportion, and in which:

Figure 1 is a diagrammatic view in elevation of the receptacle-charging device of this invention;

Fig. 2 is a diagrammatic view in elevation of the upper end of the column that supports the receptacle while it is being charged;

Fig. 3 is a sectional view along the line 33 of Fig. 2;

Fig. 4 is a sectional view along line 44 of Fig. 1, showing the supporting device for the upper part of the housing of the receptacle-charging apparatus, and with the parts within the housing omitted for the sake of greater clarity;

Fig. 5 is a diagrammatic view in elevation of a Wilson seal through which extends the column that supports the receptacle;

Fig. 6 is a diagrammatic view in elevation of the spout that delivers the vapor of the sublimable compound into the receptacle, together with surrounding portions of the vacuum container;

Fig. 7 is a sectional view along the line 77 of Fig. 6;

Fig. 8 is a vertical sectional view along the line 3-8 of Fig. 7, showing the delivery end of the vapor delivery spout that projects into the receptacle during the loading operation;

Fig. 9 is a diagrammatic view in elevation of the holder for the receptacle;

Fig. 10 is a sectional view along the line 1010 of Fig. 9;

Fig. 11 is a vertical section of a portion of the upper end of the receptacle holder and its connection to the supporting column;

Fig. 12 is a sectional view along the line 12-12 of Fig. 11;

Fig. 13 is a view, similar to Fig. 1, of a modified form of the apparatus of Fig. 1;

Fig. 14 is a diagrammatic view in elevation of a Wilson seal through which the receptacle-supporting column of Fig. 13 operates;

Fig. 15 is a diagrammatic view in elevation of the holder for the receptacle or charge bottle, and showing the position of the vapor spout at the beginning of the loading operation;

Fig. 16 is a sectional view along the line 1616 of Fig. 15;

Fig. 17 is a perspective view, partly in section, of a receptacle or charge bottle containing a solid charge of sublimable material produced in accordance with the present invention; and

Figs. 18 and 19 are diagrammatic views showing two different shapes of solid deposits of sublimable material that may be obtained by alternative procedures according to the present invention.

In broad aspect, the process of this invention comprises vaporizing a sublimable material, such as a uranium chloride, passing the vapor into a receptacle, condensing the vapor into a massive cake in the receptacle, and sealing the loaded receptacle to prevent deterioration of the contained charge. Subsequently, the receptacle or charge bottle so sealed may be placed in a calutron vaporizer and heated to vaporize the charge.

The apparatus of this invention generally comprises a sublimer or vaporizing vessel, a spout or duct for the escape of volatilized material from the sublimer, a charge bottle or other receptacle into which the sublimed material is delivered by the spout, a carrier comprising a cooled jacket or holder for the receptacle being loaded, a housing or container to enclose the receptacle and its jacket during the loading operation, and a heater for the sublimer, together with adjuvant apparatus including counterweight devices for the carrier and parts of the housing, means for refrigerating portions of the carrier and housing, means for producting a vacuum in the housing and sublimer, means for introducing inert or other special gases into the housing, the receptacle being loaded and the sublimer, means for moving the heater over and away from the sublimer, sources of electric current, etc.

Referring now to Fig. 1 of the drawings, there is shown a tubular housing fabricated of metal and comprising a lower cylinder 21 having a closed bottom and a flanged open top, an upper cylinder 22 having flanged open ends, and a closure 23. The cylinder '21 has a top flange 24 and the cylinder 22 has a bottom flange 25, by which these parts of the container are assembled in superimposed registering relation. A series of bolts, of which 26 is typical, extending through these flanges together with corresponding nuts, are used in connecting the parts 21 and 22. The rim or outer portion of the closure '23 is coextensive with a top flange 27 on the upper cylinder 22 and, when the apparatus is assembled, is held thereon by a series of bolts and nuts, of which 28 is typical. For reasons to be indicated hereinafter, the closure 23 is preferably assembled in electrically-insulated relation with respect to the top flange 27.

An annulus 31, welded to the interior wall of the lower cylinder 21, constitutes a flange to which a cover 32 is bolted by a series of bolts and nuts, of which 33 is typical (see Fig. 6), the joint between the cover and flange being made gastight by a gasket fitted into an annular groove formed in the flange. This flange and cover form a partition dividing the cylinder 21 into upper and lower chambers. In this modification, the lower chamber constitutes a sublimer in which is shown a quantity of material 34 to be sublimed. A closed thermocouple well 35, having an opening 36 through the sublimer wall, is secured to the wall of the cylinder 21, preferably by welding. A thermocouple (not shown) located in this well has two conductors 37 and 38 extending through the opening 36 and leading to suitable indicating and/or recording apparatus (not shown) outside the container. A heater 41, preferably of the electrical resistance type, encloses the subliming chamber during operation of the apparatus. The heater may conveniently comprise resistors located in a shell of refractory material, and arranged in upper, lower end bottom circuits, having leads 42 and 43, 44 and 45, and 46 and 4'7, respectively, for connection to a suitable current source or sources.

A series of brackets, of which 51 and 52 are typical, are welded to the outside of the cylinder 21 and to a frame comprising steel angle legs 53 and 54 that supports the apparatus. The heater 41 is supported in close relation about the subliming chamber by a hydraulic elevator comprising a piston 55 operating in a cylinder 56. It is thus possible by this arrangement to lower the heater to a position in which it no longer encloses the subliming chamber, thereby permitting the latter to be cooled much more rapidly.

A metal spout 61, for conducting the volatilized mate rial from the subliming chamber, is securely attached to the cover 32 by an arrangement that will be described more in detail hereinafter in connection with Fig. 6. In order to prevent cooling and consequent condensation of the vaporized material in the spout, it is preferably heated by a ribbon-like electrical resistance element 62 wrapped thereabout in a helical fashion. The upper end 63 of this heating element is firmly secured to the steel spout in any suitable manner, such as by soldering or welding. The lower end is connected to an electrical conductor 65, insulated from and extending through a vacuum-tight stufimg-box arrangement in a tubular extension 64 opening into the side wall of the cylinder -21. The heating element 62 is insulated from the spout 61 except at its upper end. The frame of the apparatus is suitably grounded, such as by wire 66 connected to leg 53, thereby providing an electrical circuit for the heating current through the conductor 65, resistance element 62, spout 61, cover 32, flange 31, cylinder 21, bracket 51 and the supporting frame including leg 53. The spout 61 is provided with-a thermocouple whose leads 59 and 60 extend through the vacuum-tight seal in the'extension 64 .of the side wall. of the. cylinder 21' to asuitable indicating and/ or recording instrument (not shown) such as a recording galvanometer, which if desired may be calibrated in such manner as to read directly in degrees centigrade. Y

The cylinder 21 has a flangedtubular lateral extension 67, through which the interior of the container may be evacuated when a vacuum is desired, or filled with helium, nitrogen, etc.,.when an inert or other special atmosphere is desired therein. A coil fabricated of copper tubing 68, or the like, is wound around the cylinder 21 above the annulus 31 and around the lateral extension 64, for the purpose of providing a path for circulating a suitable heat-exchange fluid to cool that portion of the apparatus which the coil encompasses. For convenience in maintaining the tubing 68 in proper position and in close thermal contact with the cylinder 21, thereby facilitating heat removal from adjacent surfaces, the tubing is preferably soldered to the surfaces with which it is in contact.

The upper cylinder 22 is supported by an arrangement by which it can be raised from its normally operative position in engagement with the lower cylinder 21, and held in an elevated position for purposes to be indicated later. f This elevating arrangement comprises a pair of guide rods 83 and 84, extending parallel to the axis of the cylinders 21 and 22 and fixed in position between theframe embodying the bracket 51 and a fixed upper support 75. Sliding upon the rods-83 and 84 are cylindrical members or tubes 73 and 74. Encircling the upper and lower portions of the cylinder 22 are split-ring clamps 71 and 72, which are connected to thetubes 73 and 74 by sidearms or brackets of which 70 is typical. The clamps are fixed in position on the cylinder by means of bolts and nuts extending through their laterally extending ears. The side arms are welded at their extremities to the clamps and the sliding tubes. Suitable cross-bracing is provided toconfer adequate rigidity to the clamp assembly, the details of the structure being clearly indicated in Figs. 1 and 4.

In order to-raise, lower and/or assist in supporting in desired position the cylinder 22 andappurtenant apparatus, a Windlass 76 is attached to a fixed support 77 and is provided with a cable 78 coacting therewith,'the cable operating over a pair of pulleys 79 and 80 and being securely attached to the side arm 70 that is clamped around the cylinder 22.

. Thecylinder 22, like the cylinder 21, is providedwith a cooling coil 91, fabricated of copper tubing or the like. The purpose" of this cooling arrangement is to remove heat from that portion of the cylinder 22 near the mouth of the delivery tube 61. The coil 91 is preferably soldered to the wall of the cylinder 22 to enhance the rate of heat-transfer and to secure it in position. 1 i I a I The cylinder 22 is also providedwithlaterally-extending flanged pipe extensions 92 and 93, corresponding to the extension 67 on the cylinder 21, thereby providing alternate locations for connection with'the conduit 94 through which the interior of the container may be evacuated or filled with a suitable gasp Cover plates, ,such as 95 and 96, may bebolted to the flangesof those extensions which are not being used at any given time for the evacuation of gas from, or the introduction of gas into, the interior of the container. These cover plates, illustrated as applied to the tubular extensions 92 and 93, respectively, provide gas-tight seals 'for the temporarily unused gas passages.

A bracket 85, welded to the cover 23, is provided with a socket for an incandescent lamp 86. Leads 87 and 88 from this lamp are connected to the cover 23 and the flange 27, respectively. Since the apparatus is assembled in such manner that the cover 23 is electrically insulated from the cylinder 22, the lamp serves as a visual indicator for the presence of a short circuit from the discharge spout heating circuit, including the resistance element 62, to the cover. through the assembly to the cover, the lamp will glow.

The cover 23 carries a Wilson seal through which a tubular column 102 extends and moves. This column supports a holder 103 for a receptacle or charge bottle 104. The supporting arrangement for the column 102 comprises a split-ring clamp 105 secured thereto. The clamp has laterally extending ears 112 and 113 to which suitable counter-weights are attached. Preferably, the clamp 105 is afiixed to the column 102 at a point just above the Wilson seal when the column is loweredto a position at which the bottom of the supported charge bottle is resting on the top of the discharge spout 61, so that during operation of the apparatus the position of the clamp relative to the Wilson seal will afford an indication of the relative position of the charge bottle within the container. A counterweight supporting arrangement comprises a cable 106 operating over suitably located pulleys 107, 108, 109, 110 and 111. The block of the pulley 111 is connected by a rod 114 to a suitable counter-weight 115.

A copper tube 116 adapted to carry cooling fluid, coiled about and soldered to a tube 118 constituting the upper end 'of the charge bottle supporting device, is utilized to prevent weakening or deterioration of a thermoplastic vacuum-tight sealing arrangement provided at this end of the device. A length of copper tubing 181, soldered inserpentine fashion to the charge bottle holder 103, provides cooling means for the latter. This tubing extends up through the central portion of column 102 and out through a plug 117, as indicated at 182 and 183, thus providing for the circulation of a suitable cooling fluid.

Considering Figs. 2 and 3 in detail, it will be seen that the tube 118 is relatively short and extends through the plug 117 fitted into the outer'end of the column 102. The plug 117 is welded to both the column 102 and the tube 118 to provide a vacuum-tight seal. Extending into the tube 102 via the tube 118 is a multiconductor cable 120 comprising leads 122, 123, 124, 125, 126 and 127, for three thermocouples; Filling the space between the insulating casing of the cable 120 and the tube 118 is a suitable sealing material 300, such as sealing wax or other thermoplastic material, which completes the vacuum-tight seal for the charge bottle filling device. The ends of the tube 181 carrying cooling fluid to the charge bottle holder 103 extend through the plug 117 and are soldered thereto as shown at 182 and 183.

The closure 23 and its cooperating Wilson seal, together with the upper end of the cylinder 22, are shown in detail in Fig. 5. The Wilson seal may be of conventional construction. In the form shown, it comprises an outer casing 101 consisting of a generally cup-shaped piece of steel or the like, welded to the cover 23; Resting on the bottom 131 of the outer casing 101 is a disk 132, fabricated of rubber or similar material, which is held in position by a dished washer 133. This washer has a flange 134, through which a small radial hole 135 extends, .Resting on the washer is a second rubber disk 136, and the aforementioned parts are maintained in their relative positions within the part 101 by means If current is flowing V of a plug 137. This plug and the rubber disksfit snugly about the tube 102 and snugly within the shell 101, to which latter part the plug is fastened by a series of bolts of which 138 is typical. Theshell 101 is bored at 139 to provide a hole that registers with the aperture 135 in the washer 133. A side extension tube 140 attached to the shell 101 and communicating with the bore 139 serves as a connection for applying a source of vacuum to test the tightness of the individual sealing disks 132 and 136. Wilson seals and their operation are in general well known, and consequently there is no need to burden this specification with a description of further details of same.

In Fig. 6 the central portion of the main container of the apparatus is shown on a somewhat larger scale. The vapor delivery spout 61 has diametrically opposed longitudinal grooves 151 and 152, as shown in Figs. 7 and 8, in which are positioned the leads 59 and 60 for a thermocouple (not shown) positioned near the outlet of the spout 61. These leads leave the aforementioned grooves below the lower end of the windings of the heating element 62, and pass from the interior of the cylinder 21 through the extension 64, as shown in the lower portion of Fig. 6.

Flange 24 of cylinder 21 is provided with a .pair of annular grooves to receive circular gaskets 153 and 154 that perfect the seal between the two cylinders 21 and 22. The other flange 25 is bored to provide a hole terminating in the annular space between the aforementioned gaskets at 155. Connecting with this bore is an elbow 156, which provides a connection with a suitable vacuum device for testing the tightness of the seal made by the individual gaskets when the flanges are assembled against each other. As shown in Fig. 5, a similar arrangement is provided between cover 23 and flange 27 to maintain a tight seal between cylinder 22 and its cover, and for testing the tightness of the seal therebetween.

The tube 61 is wrapped (Figs. 7 and 8) with an electrically insulating material 157, such as asbestos, paper, or the like, to prevent short circuiting of the heater winding. The resistance element 62 is wound upon the insulating material 157 which serves as a support therefor. In order to prevent loosening of the resistance element 62 and consequent slippage thereof along the spout, a spring clamp 158, having a side arm 159, is fastened around the insulating support 157 in such a position that it engages and holds the take-off portion of the heating element 62 tightly against the insulating support.

For the sake of convenience in assembling and in dismantling the vapor delivery spout 61 and associated elements for cleaning purposes, the cover 32 has welded thereon an interiorly threaded element 151 that is adapted to receive and exteriorly threaded collar 162 which is welded to, and through which extends, the spout 61.

During the loading operation, the receptacle or charge bottle 104 is fixed within the holder 103, fabricated of copper or the like, as shown in Fig. 9. The holder 103 comprises a generally cylindrical clamping sheath 171, formed by bending a piece of sheet metal, whose width is somewhat less than the circumference of the charge bottle, into a configuration closely conforming to the exterior surface of a typical charge bottle. The apposed edges of the bent sheath carry registering lugs, of which 172 and 173 are typical. One of each pair of lugs is drilled and the other tapped, to receive a bolt such as 174. The inherent resilience of the sheath enables it to be spread sufficiently to permit insertion of the charge bottle, and yet to be pulled into clamping relationship with the bottle positioned therein by drawing the lugs 172 and 173 together by means of the bolt 174, as shown more clearly in Fig. 10. After the charge bottle is clamped in the sheath, the three thermocouples 128, 129 and 130 are brought to the gap between the vertical edges of the sheath 171 (Fig. 9) and there soldered to the wall of the charge bottle itself, so that temperatures in various regions of the charge bottle may be accurately determined, and hence controlled, during operation of the apparatus.

The holder 103 also comprises a plug or shouldered disk 175, which serves as a support for the sheath 171, as shown inconsiderable detail in Figs. 9, 11 and 12. The plug has a reduced portion of approximately the same diameter as thecharge bottle which fits inside the sheath 171, and a portion of slightly larger diameter which, being in effect the top of the holder 103, serves as a point of attachment for the supporting arrangement comprising the tube or column 102. The sheath 171 is held against the reduced portion of the plug 175 by means of a series of screws, of which 176 is typical. The lower end of the tube 102 is welded to an apertured disk 177 which conforms in general shape and appearance to the exposed portion of the plug 175. The parts 175 and 177 are connected by a series of bolts, of which 178 is typical. These two parts, although connected, are maintained in spaced-apart relationby means of lock nuts, such as 179 and 180, located on each of the bolts 178.

In order to provide prompt and controlled condensation of the volatilized materialflowing from the vapor delivery spout into the charge bottle, the holder 103 is provided with a cooling arrangement that comprises primarily the tubing 181, of copper or the like, laid in a sinuous pattern about and soldered to the sheath 171, and through which a suitable coolingfluid may be passed. The inlet and discharge portions of the tubing, 182 and 183 respectively, are curved over the top of the plug 175 and into the space between the plug and the disk 177, and extend through the aperture in said disk up through the tube 102, as indicated in Figs. 1, 2, 3 and 9.

As clearly shown in Fig. 9, as the supporting column 102 is lowered the inverted charge bottle 104 having a top central opening (this opening then being directed downwardly since the charge bottle is held within the holder 103 in inverted position) is lowered until the outlet end of the vapor delivery. spout 61 is within the charge bottle, the charge bottle being in axial alignment with the spout. If this axial alignment is disturbed to a predetermined degree while the charge bottle is in operatingposition over the spout, such as by lateral displacement of the holder and charge bottle and/ or by lateral displacement of the spout, the heating element 62 will contact the top of the charge bottle, thus creating a short circuit the presence of which will be indicaed by the signal lamp. 36 already described.

A modified form of the device, constructed mainly of a high-melting glass such as Pyrex, is shown in Figs. 13 to 16. This modification is designed primarily for the treatment of sublimable compounds (or for the treatment of compounds which decompose to give sublimable compounds) at lower temperatures, and which therefore do not require for their treatment apparatus as sturdy as that shown in Figs. 1 to 12. The various elements of this apparatus correspond in general to those of the metallic device of Figs. 1 to 12.

Thus, the apparatus comprises an elongated container 222 made of glass and provided with a closure 223, constructed of stainless steel or other corrosion-resistant material. The closure 223 is secured to the container 222 in a gastight manner by providing the closure with a shoulder to receive a resilient gasket 220 (Fig. 14), formed of rubber or the like, which rests on a flange 227 formed on the upper portion of the cylinder 222, an adequate seal being maintained during operation by virtue of the atmospheric pressure working against a relatively high vacuum within the container.

As shown in Fig. 14, the closure has formed integrally therewith a Wilson seal 201 through which extends the column 202 that supports the charge bottle holder.

A vaporizing chamber 253 is formed by fusing a piece of glass 252, shaped somewhat similarly to the top of a relatively wide-mouthed bottle, to the lower wall within the container 222 and spaced sufficiently above the-bottom 9 of the container to provide a vaporizing zone of desired capacity; A vapor delivery spout 261 is fitted intothe mouth of the vaporizing'chamber by means of a stopper 254 of suitable heat-resistant material. The spout is wound with a resistance element 262 in the manner already described in connection with Figs.- 1 and 6, the resistance element having leads 224 and 225 brought out through, and sealed into, 'the'glass walls of the container. The portion of the leads within the'container are made sufficiently long topermit moving the spout and stopper to one side'while thevaporizing zone is filled with material to be processed. I j i The'container 222 has a valved'side extension 294 for connection to a source'ofvacuum orinert gas supply, as desired. j p v The column or tube 202 extends through the aforementioned Wilsonseal 201 to support a charge bottle holder 203 and charge bottle 204, the parts of this assembly beinggenerally similar to the corresponding parts of the apparatus of Fig. 1 previously described. The tube 202 is positioned by means of a bracket or clamp 205, which in turn is supported by means ofa cable 206 extending over pulleys'207, 208, 209, 210 and 211, the latter'of which is secured to a counterweight 215 by means of a connecting bar'214.

' A conventional electric heater 241 surrounds the lower portion of the container in which the material to be volatilized is located, and is provided with suitable leads 242 and 247 for connecting its resistor elements to a suitable supply of electricity.

From a consideration of the drawings, it will be seen that the device of Fig. 13 is somewhat less elaborate than that shown in Fig. 1. It is thus well suited for the processing of materials which require comparatively less drastic thermal treatment, such as the processing of uranium hexachloride which in many respects is much simpler thanthe corresponding processing of uranium tetrachloride. As a consequence, it is not necessary to provide a thermocouple on the spout 261 nor thermocouples on the charge bottle 204, although such thermocouples could be employed if desired. Rather it is generallysufficient to provide the charge bottle holder 203 with the cooling coil 281 only, and thus to that'extent simplifying the arrangement for holding thecharge bottle.

The approximate relation between the vapor delivery spout and the charge bottle at the beginning of the loading operation (for either type of apparatuslis shown in Fig. 15 of the drawings; The particular charge bottle 204 shown in Fig. 15 is of the type requiring a solderedon cap, further details of which may be found in the copending applications of Duane C. Sewell, Serial'No. 554,926, filed September 20, 1944 which issued as Patent No. 2,719,233 on September 27, 1955, and Charles H. Prescott, Jr., Serial No. 552,556, filed September 2, 1944 which issued as Patent No.. 2,574,842 on October 13, 1951. Another type of charge bottle that might be employed is shown in Fig. 17, in which after the receptaclefilling operation has been completed a seal is made by means of a piece of tin foil 302 coated on both sides with a protective layer such as a film of Glyptal resin lacquer, and held in place by means of an annular ring 303 fastened to the top of the charge bottle 104 with a series of screws 304.

Considering now the operation of the device, with particular reference to the embodiment of Fig. 1 for purposes of illustration, it is customary to elevate the charge bottle holder 103 to a position several inches above the mouth of the spout 61 and to'then move the upper cylinder 22, including the'charge bottle holder, to a position where ready access to the bottle holder may be secured; or, if this is notconvenient, the charge bottle holder may be lowered within the upper cylinder after the latter has been placed in its raised position; In either case, the receptacle .or charge bottle 104 is inverted and placed in the holder and the screws(174, etc.) tightened to.

the vaporizing'chamber. The cover is then replaced and tightened, theupper cylinder 22'is seated on the lower cylinder 21 and sealed there'to, and the charge bottle with its supportingapparatus is'rnoved downwardly within the container until the top of thespout contacts the bottom of the inverted charge bottle. Vacuum is then applied to the line'67, and when the desired degree of vacuum in the container has been attained the nozzle heater 62 is turned on. A vacuum corresponding to an absolute pressure of not more than 10- 'n1m. Hg is desirable for many materials. About ten minutes later, the vaporizer heater 41 is started, together with the various fluid cooling systems which include the circulation of a suitable cooling fluid such as air or water through the cooling coils previously described. In the foregoing description it has been assumed of course that the heater 41 has been placed in elevated positionabout the vaporizing chamber in the lower cylinder; If the clamp has not already been tightened about the tube 102, this action is taken at this time. With the vaporizer heater operating at a suitable temperature for vaporization, depending upon the nature of the material being processed, the first deposit of sublimate in the charge bottle is "ordinarily noted in a periodof time of the order of one hour. The depth of the deposit is checked at'suitable intervals, such as every fifteen minutes, by lowering the assembly cautiously until the sublimate contacts the end of the spout, and when necessary the charge-bottle supporting assembly is successively raised to positions where the nozzle is about 20 to 30 mm. below the surface of the sublimate that is being deposited 'in the charge bottle.- Ordinarily, the nozzleheater 62 is adjusted so' that the temperature of the nozzle or vapordelivery spout is about 20 higher than the temperature within the vaporizing zone in order to prevent prematurecondensation of vaporized material within or on the spout. 4

The position of the clamp 105 with respect to the Wilson seal 101 serves as an indicator for the degree to which the filling operation has taken place, thus permitting the operationto-be followed in a convenient manner.- When-the-charge bottle is filled the various heating devices are turned on and'the heater 41 is lowered from around the vaporizing chamber in order to expedite the cooling, A dry'inert gas, such as nitrogen, is introducedinto the apparatus-when the vaporizer temperature has fallen sufiiciently low, and is maintained there until the container is. opened and the charge bottle with its contents removed and sealed.

The apparatus and method of the present invention may be applied to a widevariety of sublimable materials for the purpose of producing dense solid blocks of same from a mass of such material (or from a mass of a different material which is capableof'yielding the desired material under generally similar conditions of thermal treatment, such as by dissociation under the influence of heat and/ or subatmospheric pressures) where the starting material is in a form other than the desired dense solid cake-like form, such as for example where the starting material is in the form of discrete particles. I have found that the present invention is particularly applicable to the production of dense solid masses of the particular uranium chlorides U01 and UCl and accordingly the description herein is primarily concerned with these com pounds, although without any intention whatsoever to limit the scope of the invention exclusively to the treatmentor production of these, named compounds.

H By way of further explanation, it-maybe stated that the thermal conditions under which there is obtained the desired dense solid mass of the desired-material will of course vary somewhat, depending upon the nature of the compound that 'formsthe starting material. For example, when treating nranium hexachloride, such as in the form of discrete particles, in accordance with the inventionfor the purpose of producing that compound in massive form, the condensate or sublimate of uranium hexachloride usually begins to appear in thecharge bottle when the charge in the vaporizing chamber has reached a temperature of approximately 80 C. under the particular vacuum conditions obtaining, for example, under a vacuum corresponding to an absolute pressure of not more than approximately mm. Hg. However, temperatures somewhat in excess of 150 C., for example in therange of approximately 150 to 190 C., are preferred forthe sublimation of this material at a practicable rate. In fact, the sublimation of uranium hexachloride may be carried out at temperatures approaching 210 C. for short times. The use of the higher temperature for extended periods is ordinarily not desired because uranium hexachloride begins to decompose slightly vat 100 C., and at an appreciable rate above 150 C. in vacuo, and consequently the advantage of increased rate of sublimation tends to become ofiset by the increased rate of decomposition of the product if the temperature is raisedto an undue extent.

Instead of treating a finely divided uranium hexachloride to obtain a highly purified uranium hexachloride product .in the desired massive form as described above, uranium pentachloride may be employed as the starting material for the production of uranium hexachloride by the general reaction mechanism disclosed and claimed in the copending application of Francis A. Jenkins, Serial No. 494,447, filed July 13, 1943, which issued as Patent No. 2,572,156 on October 23, 1951; Le, by the disproportionation of uranium pentachloride into uranium hexachloride and uranium tetrachloride under the influence of heat and vacuum. When uranium pentachloride is used as the starting material, it is heated in the vaporizing zone to a temperature ranging from about 80 to about 180 C., but preferably toward the upper end of this range. Temperatures as. high as 250 C. may be employed for relatively short periods so as not to cause undue thermal decomposition of the thus-produced uranium hexachloride. At elevated temperature and subatmospheric pressure, the uranium pentachloride is decomposed into uranium tetrachloride and uranium hexachloride, the latterpassing out of the heated zone in the form of vapor which flows through the vapor delivery spout and into the cooled charge bottle where it is condensed in massive form in the manner described above. A residue, mainly uranium tetrachloride, of over 50% of the original material is left inthe vaporization zone from which it may be recovered and employed for other purposes as desired.

When it is desired to produce uranium tetrachloride in massive form in accordance with the present invention, it is necessary to employ considerably higher temperatures in the vaporization zone, since uranium tetrachloride is considerably less volatile than uranium hexachloride. In this case the uranium tetrachloride in particle form, and either pure or containing more or less impurities, is placed in the vaporization zone and subjected to temperatures of the order of at least 500 C. under a vacuum corresponding to an absolute pressure of not more than approximately 10* mm. Hg. Temperatures as low as 400 C. maybe employed for vaporization but, generally speaking, temperatures in the range of about 500"v to 550C. are preferred for ordinary operation. Temperatures as high as 600 C. have been employed with satisfactory results.

In view of the fact that the-vaporizing temperatures that are employed whenprocessing uranium tetrachloride are considerably higher than the temperatures that are suitable when processing uranium hexachloride or uranium pentachloride, it'ispreferredto employ the apparatus shown in Figs. 1 to .12 when treating the tetrachloride, whereas'the apparatusshown in Figs. .13 to .16 may be employed when processing either the pentachloride or the hexachloride to produce the hexachloride in massive form. Similarly, when processing other sublimable materials in accordance with the present invention, the choice as to which apparatus embodiment is to be preferably employed will be dictated by the properties of the given material, and especially by its relative volatility.

Since the compounds which the apparatus herein was primarily designed to process are corrosive and/or give rise to corrosive substances under the thermal conditions encountered therein, it is desirable in view of the relatively elevated temperatures employed to use specially. selected materials of construction for the apparatus. Thus in the modification illustrated in Figs. 1 to 12, except where otherwise mentioned or indicated, the parts of the apparatus that are exposed to these corrosive influences are preferably made of a high-scaling stainless steel stock, such as 18-8 (18% Cr, 8% Ni; U.S.S. #316), in order to resist corrosion by the chlorine-containing materials present in the apparatus. Parts not subjected to high temperatures or to uranium chloride or other corrosive vapors may be fabricated of other construction materials appropriate for the purpose, such as carbon, steel, brass, copper, and the like. As alreadyindicated, the apparatus embodiment shown in Figs. 13 to 16 is fabricated largely of Pyrex glass, except where otherwise indicated. For example,the Wilson seal 201, the charge bottle 204, the closure 223, the supporting mechanism for the charge bottle, and the vapor delivery spout 261 are fabricated of stainless steel or other corrosion-resistant material.

When the charge bottle is filled while causing relative movement between the mouth of the vapor delivery spout and the charge bottle, a solid cake of sublimed material with a small, generally conical-shaped depression as a final deposit surface is obtained, this being illustrated in Fig. 18. It will be apparent that in this case the majority of the effusing molecules always strike the end of the open space that is in alignment with the vapor delivery spout, rather thanthe side wall of the charge bottle.

On the other hand, and as a variation in the bottle or receptacle charging operation described above, the open end of the vapor delivery spout may be positioned within the bottle and left stationary during the entire filling operation. In such a case, the deposit of sublimed material in dense massive form builds up mainly along the charge bottle wall that is in the vicinity of the outlet of the spout, so that a vacant tubular space generally resembling a chimney or hour-glass formation is left in the receptacle or charge bottle. The shape of the deposit formed in a charge bottle in such a manner is illustrated in Fig. 19. It may be pointed out that there are instances when it may be desirable to have the sublimed material in such shape; for example, when preparing a uranium halide such as the tetrachloride or hexachloride for use as the charge material fora calutron. In this modification, while the sublimed material does not fill substantially the entire volume of the receptacle, nevertheless it is in dense massive form otherwise similar to that of Figs. 17 and 18.

As demonstrating the efficacy of the hereindescribed process for preparing sublimable, normally solid materials in dense massive form, it may be noted that the bulk or apparent density of uranium hexachloride in powdered form as ordinarily obtained is approximately 1.75 grams per cubic centimeter, whereas the bulk density of uranium hexachloride in massive form as obtained by the present process is 3.36- -0.17 grams per cubic centimeter. With this technique it is thus possible to put approximately twice as much uranium hexachloride in a given receptacle.

While the particular apparatus embodiments disclosed herein provide for movement of the receptacle or charge bottle while the vapor delivery spout is maintained in fixed position, it is to be understood that it is within the 13 .1 I spirit of the invention to so construct the apparatus that the charge bottle is stationary and-the vapor delivery spout is caused to move, or alternatively to so construct the apparatus that both these elements move with respect to each other. In other words, the relative motion between these two elements may be produced in any desired manner. Furthermore, ,instead of manually adjustingthe position of the. charge bottle with respect to the outlet of the vapor delivery spout during the,filli ng operation, automatic mechanism may be provided for this purpose,

such as a clockwork arrangement whereby the desired motion at a predetermined rate of speed is imparted to the parts in question.

The advantages of the previously described apparatus and process will be apparent from the foregoing description and the drawing. Particular attention, however, may be directed to certain features. The dense blocks or bricks of uranium chlorides produced in situ in the charge bottle enable the calutron Vaporizers to come to thermal equilibrium with the charge in a much shorter time, thereby producing greater stability in other parts of that apparatus. Lower temperatures for the major portion of the calutron run are obtainable with the dense deposits. Greater quantities of material can be placed in a standard charge bottle when deposited in the manner described above, and consequently the calutron throughputs are increased. Furthermore, a more highly purified product is obtained since any relatively non-volatile impurities, e.g., oxyhalides such as uranium oxychlorides, that might have been present originally in the starting material are left behind in the vaporizing chamber.

Many apparently widely different embodiments of this invention may be made without departing from the principle, breadth and spirit thereof and it is to be understood, therefore, that this invention is not limited to the specific embodiments shown herein except as encompassed by the following claims.

What is claimed is:

1. Apparatus for filling a tubular storage receptacle with a uranium chloride in dense massive form comprising a closured cylindrical housing including a transverse partition therein dividing the interior volume of the housing into a portion adapted to receive said receptacle in which receptacle the walls define a condensation zone and the remainder into a uranium chloride vaporizing chamber, a storage receptacle disposed in said receptacle portion of the housing, nozzle means communicating with said vaporizing chamber and extending into the interior of said receptacle for conducting uranium chloride vapors into the condensation zone therein, means for cooling the walls of said receptacle below the triple point of said uranium chloride, means for evacuating said housing to the level at which the mean free path of the molecules is at least of the order of the dimension of the condensing zone in said receptacle, and means supporting said receptacle and operable through a vacuum seal in said housing to provide longitudinal movement of the receptacle with respect to said nozzle.

2. Apparatus for filling a tubular receptacle with a uranium chloride in dense massive form comprising a closured cylindrical housing partitioned to provide a uranium chloride vaporizing chamber in one portion thereof and a second chamber adapted to receive said receptacle in which receptacle the walls define a condensation zone, means for producing a vacuum in said housing wherein the molecular mean free path is at least of the order of the dimension of the condensation zone in said receptacle, a tubular receptacle disposed in said receptacle chamber, nozzle means communicating with said vaporizing chamber and projecting within said tubular receptacle v to conduct uranium chloride vapors into the condensation zone therein, means operable from the exterior of said housing positioning said receptacle in axial alignment with said nozzle and adjusting the longitudinal engagement therebetween, and means for cooling the walls of said receptacle below the triple point of said uranium.

chloride to efiect deposition thereof in said dense massive form. 3. Apparatus for. filling a.tubular receptacle with a uranium chloride in dense massive form comprising avertically disposed closured cylindrical housing transversely partitioned to provide a uranium chloride vaporiz ing chamber in the lower portion thereof and an upper chamber adapted to receive said receptacle in which receptacle the walls define a condensing zone, means for producing a vacuum in said housing wherein the mean free path of the uranium chloride molecules is at least equivalent to the dimensions of the condensing zone in said receptacle, a tubular receptacle disposed vertically in the upper chamber of said housing, a nozzle communieating with said vaporizing chamber extending upwardly in substantially axial alignment into the condensing zone in said receptacle, means operable from the exterior of said housing supporting and positioning said receptacle in axial alignment and adjusting the longitudinal engagement therebetween, means associated with said supporting means for cooling the walls of said receptacle below the triple point of said uranium chloride, and means for heating said nozzle to at least about 20 C. above the temperature in said vaporizing chamber to prevent deposition of uranium chloride therein.

4. Apparatus for filling a tubular receptacle with a uranium chloride in dense massive form comprising a vertically disposed closured cylindrical housing transversely partitioned to provide a uranium chloride vaporizing chamber in the lower portion thereof and an upper chamber adapted to receive said receptacle in which receptacles the walls define a condensing zone, means for heating said vaporizing chamber to a temperature above the sublimation point of said uranium chloride, means for producing a vacuum in said housing wherein the mean free path of the uranium chloride molecules is at least equivalent to the dimensions of the condensing zone in said receptacle, a tubular receptacle disposed vertically in the upper chamber of said housing, a nozzle communicating with said vaporizing chamber and extending upwardly in substantially axial alignment into the condensing zone in said receptacle, means operable from the exterior of said housing supporting and positioning said receptacle in axial alignment and adjusting the longitudinal engagement therebetween, means associated with said supporting means for cooling the walls of said receptacle below the triple point of said uranium chloride, and means for heating said nozzle to at least about 20 C. above the temperature in said vaporizing chamber to prevent deposiiton of uranium chloride therein.

5. Apparatus for filling a tubular receptacle with a uranium chloride in dense massive form comprising a vertically disposed closured cylindrical housing transversely partitioned to provide a uranium chloride vaporizing chamber in the lower portion thereof and an upper chamber adapted to receive said receptacle in which receptacle the walls define a condensing zone, means for heating said vaporizing chamber to a temperature above the sublimation point of said uranium chloride, means for producing a vacuum in said housing wherein the mean free path of the uranium chloride molecules is at least equivalent to the dimensions of the condensing zone in said receptacle, a tubular receptacle disposed vertically in the upper chamber of said housing, a nozzle communicating with said vaporizing chamber and extending upwardly in substantially axial alignment into the condensing zone in said receptacle, means including a tubular column extending upwardly through a vacuum seal disposed terminally in said housing and constructed at the lower end to engage and support said receptacle, said 'means thereby being operable from the exterior of said said supporting means for cooling the walls of said receptacle below the triple point of said uranium chloride, and means for heating said nozzle to at least about 20 C. above the temperature in said vaporizing chamber to prevent deposition of uranium chloride therein.

References Cited in the file of this patent UNITED STATES PATENTS 16 Amati Oct. 7, 1941 Prescott Apr. 3, 1951 Jenkins Oct. 23, 1951 Hecker Apr. 24, 1956 Krohn Q. May 29, 1956 OTHER REFERENCES Friend: Textbook of Inorganic Chemistry, vol. VII, pt. III, pp. 294, 295 (1926). Publ. by Charles Griflin &

Noble Sept. 13, 1932 10 C o.,-Ltd.,'London. 

1. APPARATUS FOR FILLING A TUBULAR STORAGE RECEPTACLE WITH A URANIUM CHLORIDE IN DENSE MASSIVE FORM COMPRISING A CLOSURED CYLINDRICAL HOUSING INCLUDING A TRANSVERSE PARTITION THEREIN DIVIDING THE INTERIOR VOLUME OF THE HOUSING INTO A PORTION ADAPTED TO RECEIVE SAID RECEPTACLE IN WHICH RECEPTACLE THE WALLS DEFINE A CONDENSATION ZONE AND THE REMAINDER INTO A URANIUM CHLORIDE VAPORIZING CHAMBER, A STORAGE RECEPTACLE DISPOSED IN SAID RECEPTACLE PORTION OF THE HOUSING, NOZZLE MEANS COMMUNICATING WITH SAID VAPORIZING CHAMBER AND EXTENDING INTO THE INTERIOR OF SAID RECEPTACLED FOR CONDUCTING URANIUM CHLORIDE VAPORS INTO THE CONDENSATION ZONE THEREIN, MEANS FOR COOLING THE WALLS OF SAID RECEPTACLE BELOW THE TRIPLE POINT OF SAID URANIUM CHLORIDE, MEANS FOR EVACUATING SAID HOUSING TO THE LEVEL AT WHICH THE MEAN FREE PATH OF THE MOLECULES IS AT LEAST OF THE ORDER OF THE DIMENSION OF THE CONDENSING ZONE IN SAID RECEPTACLE, AND MEANS SUPPORTING SAID RECEPTACLE AND OPERABLE THROUGH A VACUUM SEAL IN SAID HOUSING TO PROVIDE LONGITUDINAL MOVEMENT OF THE RECEPTACLE WITH RESPECT TO SAID NOZZLE. 